1. Field of the Invention
The present invention relates to a playback apparatus with a structure for preventing wrong-insertion of a recording medium such as a CD-ROM.
2. Description of the Related Art
Hitherto, apparatuses that play back a recording medium such as a CD-ROM are widely known as in-vehicle audio equipment (playback apparatuses).
Such audio equipment has, as shown in FIG. 7, a playback apparatus 3 including a playback device 1, serving as a casing, and a control panel 2. A shutter base 5 is fixed using screws 4 to the rear side of the control panel 2. A shutter member 6 is pivotably mounted on the shutter base 5.
The playback device 1, which can receive a plurality of CD-ROMs, encases a CD-ROM receiving mechanism, a selector for selecting a designated CD-ROM, a pickup device for playing back the selected CD-ROM, and associated parts (none of which are shown). Also, the playback device 1 has an opening 1a into which the CD-ROM is inserted and a lever 7 for pivoting the shutter member 6 with its forward movement, the tip of the lever 7 projecting from the opening 1a. 
The control panel 2 is attached to the playback device 1 and various selectable switches are provided on the front face of the control panel 2. The control panel 2 also has a display 2b, a cassette tape loading slot 2c, and so on, as well as a CD-ROM loading slot 2a, which is aligned with the opening 1a. 
The shutter base 5 has a passage 5a for the CD-ROM to pass through between the loading slot 2a and the opening 1a, and a shaft 5b (only one end is shown) for pivotably supporting the shutter member 6. A pin 5c for retaining one end of a spring 8 protrudes from the shutter base 5.
The shutter member 6 has a pin 6a for retaining the other end of the spring 8, a shutter blade 6b for blocking the spatial communication between the loading slot 2a and the passage 5a with the elastic force of the spring 8, and an arm 6c, which is contactable with the tip of the lever 7. When the lever 7 moves toward the front of the playback apparatus 3 and the tip of the lever 7 pushes the arm 6c, the arm 6c causes the shutter blade 6b to pivot.
In such a configuration described above, for example, when the CD-ROM is played back or when the mechanism for sequentially receiving a plurality of CD-ROMs is being driven, it is necessary to prevent another CD-ROM from being loaded into the playback device 1. To this end, the shutter blade 6b is moved by the elastic force of the spring 8, so as to block the spatial communication between the loading slot 2a and the passage 5a. 
When loading of a CD-ROM is permitted, the lever 7 moves toward the front of the playback apparatus 3 and pushes the arm 6c in order to pivot the shutter member 6 to overcome the elastic force of the spring 8, thus again allowing the spatial communication between the loading slot 2a and the passage 5a. 
In a playback apparatus with a structure for preventing wrong-insertion of a recording medium constructed as described above, when the CD-ROM is inserted at an upward angle from a lower position, as shown in FIG. 8B, while the shutter member 6 blocks the spatial communication between the loading slot 2a and the passage 5a, as shown in FIG. 8A, the leading edge of the CD-ROM abuts against a part around the center in the width direction of the shutter blade 6b, because the CD-ROM is a thin disc.
At this time, due to the load applied by the inserted CD-ROM and the fact the shutter blade 6b is wide, as shown in FIG. 8C, flexing of the shutter blade 6b may occur as a result, so that the central part thereof is displaced toward the passage 5a. Any additional load may cause the CD-ROM to enter into the space between the uppermost edge of the shutter blade 6b and the shutter base 5, resulting in the shutter blade 6b unintentionally pivoting. Accordingly, there is the possibility that the CD-ROM may be accidentally inserted into the playback apparatus.
When the CD-ROM is inserted at a downward angle from an upper position while the shutter member 6 blocks the spatial communication between the loading slot 2a and the passage 5a, as shown in FIG. 9A, there is the possibility that the load applied by the inserted CD-ROM may cause the shutter blade 6b to unintentionally pivot, as shown in FIG. 9B.